This invention relates to microfluidic devices.
The existence of dead volumes is a recognized problem in systems comprising microfluidic devices. Dead volumes are particularly likely to exist at junctions between different microfluidic conduits and between microfluidic devices and conventional capillaries and other macroscopic apparatus. Dead volumes are particularly undesirable in analytical apparatus, because they cause dispersion in samples derived from, or directed to, liquid chromatography columns, and disturb the distribution of particles in samples to be examined in cytometry and like procedures.
The making of junctions comprising microfluidic conduits (for example junctions between a microfluidic conduit and a conventional elongate component, e.g. a capillary tube, optical fiber or electrical lead) presents many problems. The problems increase when a plurality of closely-spaced junctions must be made, and/or it is desirable to make a junction which can be disassembled, e.g. to remove debris. Known methods of making such junctions are disclosed, for example, in U.S. Pat. Nos. 6,605,472, 6,319,476, 6,620,625 and 6,832,787, U.S. Patent Application Publication Nos. US 2002/0043805 and 2003/0173781, International Publication Nos. WO/98/25065, WO/98/33001, WO 00/52376, WO 01/86155, and WO 02/070942, Sensors and Actuators B 49, 40-45 (1998) (Gonzales et al), Anal. Methods Instrum. 2 (1995) 74 (Ockvirk et al), Anal. Chem. 71, 3292 (1999) (Bings et al), Lab-on-a-Chip 1, 148-152 (2001) (Nittis et al), and Lab-on-a-Chip 2, 42-47(2003) (Kopf-Sill), the entire disclosures of which are incorporated herein by reference for all purposes.